Cooling apparatus

ABSTRACT

A heat sink comprises a core member comprising at least one first surface adapted to contact at least a portion of the heat source. An one outer peripheral surface is located on the core member. At least one cooling fin device comprising an inner peripheral surface and at least one cooling fin is adjacent the core member. In one embodiment, the inner peripheral surface of the cooling fin device is adjacent the outer peripheral surface of the core member. At least a portion of the outer peripheral surface is tapered, wherein the circumference of the outer peripheral surface in the proximity of the first surface is greater than the circumference of the outer peripheral surface not in the proximity of the first surface.

[0001] This application is a continuation-in-part of U.S. applicationSer. No. 10/006412 of Wagner filed on Dec.3, 2001, which is herebyincorporated by reference for all that is disclosed therein.

FIELD OF THE INVENTION

[0002] The present invention relates generally to cooling devices.

BACKGROUND OF THE INVENTION

[0003] Electronic components, such as integrated circuits, areincreasingly being used in different devices. One prevalent example of adevice using integrated circuits is the computer. The central processingunit or units of most computers, including personal computers, istypically constructed from a plurality of integrated circuits.Integrated circuits are also used in other computer circuitry. Forexample, interface and memory circuits typically comprise severalintegrated circuits.

[0004] During normal operation, many electronic components, such asintegrated circuits, generate significant amounts of heat. If this heatis not continuously removed, the electronic component may overheat,resulting in damage to the component and/or a reduction in its operatingperformance. For example, an electronic component may encounter thermalrunaway, which may damage the electronic component. In order to avoidsuch problems caused by overheating, cooling devices are often used inconjunction with electronic components.

[0005] One such cooling device used in conjunction with electroniccomponents is a heat sink. A heat sink is a device that draws heat froman electronic component and convects the heat to the surroundingatmosphere. The heat sink is usually placed on top of, and in physicalcontact with, the heat generating electronic component so as to providethermal conductivity between the electronic component and the heat sink.

[0006] One method of increasing the cooling capacity of heat sinks is byincluding a plurality of cooling fins attached to the heat sink and acooling fan that forces air past the cooling fins. The cooling finsserve to increase the surface area of the heat sink and, thus, increasethe convection of heat from the heat sink to the surrounding atmosphere.The fan serves to force air past the fins, which further increases theconvection of heat from the heat sink to the surrounding atmosphere.This increased convection, in turn, allows the heat sink to draw moreheat from the electronic component. In this manner, the heat sink isable to draw a significant amount of heat away from the electroniccomponent, which serves to further cool the electronic component.

[0007] Cooling fins with larger surface areas, however, tend to havesignificant barrier layers of air on the cooling fin surfaces when airis forced past the cooling fins. An air barrier layer is air that isadjacent the surface of a cooling fin and remains substantiallystationary relative to the cooling fin as air is forced past the coolingfin. Thus, a significant barrier layer may result in the air beingforced past cooling fins not being able to effectively remove heat fromthe cooling fins. Accordingly, increasing the area of individual coolingfins may not result in a proportional cooling capability of the heatsink.

[0008] Another problem associated with large cooling fins is that theyoccupy large spaces within an electronic device, which could otherwisebe used to reduce the size of the electronic device. Large cooling finsalso occupy space that could otherwise be used to increase theconcentration of electronic components located within the electronicdevice. Electronic devices are becoming much smaller, thus, a reducedspace or a higher concentration of electronic components within theelectronic devices is beneficial. The use of large cooling fins tends toincrease the size of the electronic devices or reduce the concentrationof electronic components located therein.

[0009] Therefore, a device and/or method is needed to overcome some orall the aforementioned problems.

SUMMARY

[0010] An embodiment of the present invention is directed toward a heatsink for removing heat from a heat source. The heat sink may comprise acore member comprising at least one first surface adapted to contact atleast a portion of the heat source. An one outer peripheral surface islocated on the core member. At least one cooling fin device comprisingan inner peripheral surface and at least one cooling fin is adjacent thecore member. In one embodiment, the inner peripheral surface of thecooling fin device is adjacent the outer peripheral surface of the coremember. At least a portion of the outer peripheral surface is tapered,wherein the circumference of the outer peripheral surface in theproximity of the first surface is greater than the circumference of theouter peripheral surface not in the proximity of the first surface.

BRIEF DESCRIPTION OF THE DRAWING

[0011]FIG. 1 is a top perspective view of a cooling device having aplurality of fin rings and a fan.

[0012]FIG. 2 is a top perspective view of the cooling device of FIG. 1having a single first fin ring and without the fan.

[0013]FIG. 3 is a top perspective view of the core member of the coolingdevice of FIG. 1.

[0014]FIG. 4 is a side view of the core member of the cooling device ofFIG. 1 without any fin rings associated therewith.

[0015]FIG. 5 is a cut away, schematic illustration of the cooling deviceof FIG. 1.

[0016]FIG. 6 is a side view of the cooling device of FIG. 1 locatedadjacent a heat generating electronic device.

[0017]FIG. 7 is a top perspective view of a fin ring of the typeillustrated in the cooling device of FIG. 2.

[0018]FIG. 8 is a top perspective view of the cooling device of FIG. 2having a second fin ring located adjacent the first fin ring.

[0019]FIG. 9 is a side view of the cooling device of FIG. 6 with ashroud attached thereto.

[0020]FIG. 10 is a top perspective view of the cooling device of FIG. 2with the addition of a compression ring.

[0021]FIG. 11 is a side view of the cooling device of FIG. 1 with aplurality of compression rings attached thereto.

[0022]FIG. 12 is a top cutaway view of a cooling device having aribbon-type cooling fin associated therewith.

[0023]FIG. 13 is the cooling device of FIG. 12 with the addition of ashroud encompassing the core and ribbon-type cooling fin.

[0024]FIG. 14 is a side, schematic illustration of a cooling devicehaving cooling fins extending parallel to the core.

[0025]FIG. 15 is a side view of an embodiment of the core member of FIG.3 being constructed from two components.

[0026]FIG. 16 is a side view of a cooling device having a reducedshroud.

DETAILED DESCRIPTION

[0027] A non-limiting embodiment of a cooling device 100 is shown inFIG. 1. The cooling device 100 may have an air blowing device 110associated with a heat sink 200. In the non-limiting embodimentdescribed herein, the air blowing device 110 is a fan and is sometimesreferred to as the fan 110. However, it is to be understood that the airblowing device 110 may be other devices, such as duct work that causesair to be blown onto the heat sink 200. The following descriptiondescribes the heat sink 200 followed by a description of the fan 110. Adescription of the operation of the fan 110 associated with the heatsink 200 follows their individual descriptions.

[0028] Referring to FIG. 2, which shows a partially constructed heatsink 200, the heat sink 200 may have a core member 210 (sometimesreferred to herein simply as the core 210) with a first fin ring 281located adjacent the core 210. For illustration purposes, FIG. 2 showsonly a single first fin ring 281 attached to or otherwise operativelyassociated with the core 210. Further below in this description, theheat sink 200 will be described having a plurality of fin rings 240,FIG. 1, operatively associated with the core 210. The first fin ring 281and other fin rings described herein are sometimes referred to ascooling fin devices.

[0029] A top perspective view of the core 210 is shown in FIG. 3. Theview of FIG. 3 is similar to the core 210 of FIG. 2 without any finrings attached thereto. The core 210 may be made of a thermallyconductive material, such as copper or aluminum. The core 210 may have atop surface or portion 214 and a lower surface or portion 216. A heightH1 may extend between the top portion 214 and the lower portion 216 andmay, as an example, be approximately 3.0 centimeters. The top portion214 may be substantially round and may have a diameter D1 associatedtherewith. The diameter D1 may, as an example, be approximately 3.0centimeters. The diameter D1 and height H1, however, are dependent onthe specific cooling application of the cooling device 100 and may varyaccordingly both in size and shape.

[0030] The core 210 may have an outer peripheral surface 212 (sometimessimply referred to herein as the peripheral surface 212) located betweenthe top portion 214 and the lower portion 216. The peripheral surface212 of the core 210 has a cylindrical portion 217 and a tapered portion218. It should be noted that the use of a partially cylindrical coreand, thus, a cylindrical portion 217 is for illustration purposes only.The core 210 may be virtually any shape that serves to allow the finrings to be associated therewith. For example, the core 210 and, thus,the top portion 214, may be oval. It should also be noted that the core210 shown in FIG. 3 has a single peripheral surface 212. Otherembodiments of the core 210 may have several peripheral surfaces. Forexample, the peripheral surface 212 may be divided into several portionsor may form several surfaces.

[0031] The cylindrical portion 217 of the core 210 has a height H2 andthe tapered portion 218 has a height H3. As shown in FIG. 3, thecylindrical portion 217 of the core 210 extends between the top portion214 and a portion of the peripheral surface 212 indicated by a dashedline. The tapered portion 218 extends between the dashed line and thelower portion 216. In the embodiment described herein, the fin ringsshown in FIG. 2 are attached to the cylindrical portion 217 of the core210. As described in greater detail below, the tapered portion 218serves to divert air from the core 210, which increases the efficiencyof the heat sink 100, FIG. 1.

[0032] Referring to FIG. 4, which is a side view of the core 210 of FIG.3, the lower portion 216 of the core 210 is adapted to be in thermalcontact or physical contact with a heat generating device 330. In theembodiment described herein, the lower portion 216 of the core 210 isadapted to contact a top surface 332 of the heat generating device 330.The contact between the core 210 and the heat generating device 330provides for the transfer of heat from the heat generating device 330 tothe core 210. For example, in the situation where the heat generatingdevice 330 is an integrated circuit, the top surface 332 of theintegrated circuit is typically a planar surface. Accordingly, the lowerportion 216 of the core 210 may be a substantially planar surface andmay have an area that is approximately the same as or greater than thearea of the top surface 332 of the heat generating device 330.

[0033] As shown in FIG. 3 and FIG. 4, the circumference or perimeter ofthe peripheral surface 212 of the core 210 is the greatest in theproximity of the lower portion 216 of the core 210. More specifically,the circumference of the peripheral surface 212 increases in the taperedportion 218 of the core 210 toward the lower portion 216 of the core210. Accordingly, the circumference is at a minimum in the proximity ofthe cylindrical portion 217 of the core and is at a maximum in theproximity of the lower portion 216. This tapering of the core 210 causesairflow generated by the air blowing device 110 to be freely exhaustedaway from the lower portion 216 of the core 210 as shown in FIG. 4. Asthe airflow transitions from a direction toward the heat generatingdevice 330 to a direction away from the heat generating device 330, backpressure and/or turbulence are reduced by the tapered portion 218.Therefore, a greater amount of air may pass adjacent the core 210 andmay remove a greater amount of heat from the core 210. With anadditional and brief reference to FIG. 1, the tapering of the core 210enables a greater amount of air to pass the cooling fins, which in turnincreases the cooling capability of the heat sink 200.

[0034] The airflow shown in FIG. 4 is parallel to the peripheral surface212. More specifically, the airflow is shown commencing at the airblowing device 110 and extending in a substantially straight line to thetapered portion 218, where it is then terminated by being exhausted fromthe heat sink 200. Such an airflow may exist in a situation where theairflow generated by the air blowing device 110 extends substantiallynormal to the air blowing device 110. For example, this airflow mayexist in a situation where the air blowing device 110 is a duct thatdelivers forced air from a remote location.

[0035] Referring briefly to FIG. 5, an embodiment of the cooling device100 may have an airflow that spirals the core 210. For example, in asituation where the air blowing device 110 is a fan, the airflow maysubstantially spiral around the core 210 as is described in greaterdetail below. With additional reference to FIG. 1, the spiraling airflowshown in FIG. 5 improves the airflow associated with the fin rings as isdescribed in greater detail below.

[0036] Referring again to FIG. 4, in the embodiment of the core 210illustrated herein, the peripheral surface 212, including thecylindrical portion 217 and the tapered portion 218, are continuous,meaning that there are no discontinuities in the peripheral surface 212.The continuous surfaces enable the airflow shown in FIG. 4 to be lesssusceptible to turbulence and enables greater airflow. In anotherembodiment of the core 210, the peripheral surface 212 hasdiscontinuities (not shown) and, thus, only portions of the peripheralsurface 212 contact the fin rings, FIG. 2.

[0037] Having described the core 210, FIG. 2, the first fin ring 281,FIG. 7, will now be described in greater detail. FIG. 7 is a topperspective view of the first fin ring 281 separated from the core 210,FIG. 2, and is representative of the remaining fin rings 240 that may beassociated with the core 210 as illustrated in FIG. 6. The first finring 281 may have a collar 244 with a plurality of cooling fins 246attached thereto or otherwise associated therewith. The collar 244 mayhave an inner peripheral surface 248 having an upper ring portion orside 270 and a lower ring portion or side 272. The upper portion 270 andthe lower portion 272 may be separated by a height H3, which may, as anexample, be approximately 0.25 centimeters. The upper ring portion 270and the lower ring portion 272 may be located on substantially parallelplanes. A reference axis BB may pass through the center point 274 of acircle defined by the collar 244. The reference axis BB may besubstantially normal to the planes defined by the upper ring portion 270and the lower ring portion 272.

[0038] The inner peripheral surface 248 has a perimeter associated withit, which in the embodiment described herein is a cylindrical surfaceextending between the upper portion 270 and the lower portion 272. Theperimeter of the inner peripheral surface 248 may be substantiallysimilar to the perimeter of the cylindrical portion of the peripheralsurface 212, FIG. 2, of the core 210. For example, the inner peripheralsurface 248 may be round and may have a diameter D2 that isapproximately the same or slightly smaller than the diameter D1 of thecore 210, FIG. 2. In one embodiment of the heat sink 200, FIG. 2, thediameter D1 of the core 210 and the diameter D2, FIG. 7, of the firstfin ring 281 are appropriately sized so as to cause an interference fitbetween the first fin ring 281 and the core 210 as is described ingreater detail below.

[0039] The collar 244 may have an outer surface 252 wherein the coolingfins 246 are attached to the outer surface 252. Reference is made to afirst fin 250, which is representative of all the cooling fins 246 andtheir association with the outer surface 252. The first fin 250 may havea mounting portion 256, an end portion 258, a surface 260, an upper end262, and a lower end 264. The surface 260 may be defined by theboundaries of the mounting portion 256, the end portion 258, the upperend 262, and the lower end 264. The surface 260 may be substantiallyplanar. A length D3 may extend between the mounting portion 256 and theend portion 258. The length D3 may, as an example, be approximately 11to 13 millimeters. A length D4 may extend between the upper end 262 andthe lower end 264. In one embodiment the length D4 is relatively smallin order to reduce the boundary layer of air that may accumulate on thesurface 260 of the first fin 250 when air is forced past the surface260. The length D4 may, as an example, be approximately 3.25millimeters. The mounting portion 256 may be a twisted portion of thefirst fin 250 and may serve to create an angle φ between the end portion258 and the reference axis BB. The angle φ may, as an example, beapproximately45 degrees. It should be noted that the angle φ may bedetermined by the direction of the airflow as shown in FIG. 4 and FIG. 5and as described in greater detail below.

[0040] The collar 244 and the cooling fins 246 may be made of a heatconducting material such as aluminum or copper. The junction between thecollar 244 and the mounting portion 256 of the cooling fins 246 mayconduct heat with minimal thermal resistance. For example, the collar244 may be integrally formed with the cooling fins 246 or they may bewelded together. In a non-limiting example of manufacturing the firstfin ring 281, the first fin ring 281 may be fabricated from a singlemetal sheet, such as a copper or aluminum sheet. The metal sheet may, asan example, have a thickness of approximately 15 to 20 thousandths of aninch. Fabrication of the first fin ring 281 may commence with stampingthe collar 244 out of the metal sheet. The collar 244 is essentially acircular cutout having a diameter D2 and a height H2. Accordingly, thestamping process forms the diameter D2 and the height H2 of the collar244. The cooling fins 246 may then be stamped out of the metal sheet.For example, the cooling fins 246 may be cut out of the metal sheet viaa conventional stamping process. The metal sheet may then be placed intoa dye that twists the cooling fins 246 at the mounting portion 256 inorder to form the angle φ.

[0041] Referring again to FIG. 2 and FIG. 4, the first fin ring 281 maybe pressed onto the core 210 in a conventional manner to form aninterference fit between the first fin ring 281 and the core 210. Theinterference fit is a result of a cylindrical portion 217 of the surface212 of the core 210 being substantially the same as the perimeter of theinner peripheral surface 248, FIG. 7, of the first fin ring 281.Accordingly, the diameter D1 of the core 210 is substantially the sameor slightly larger than the diameter D2, FIG. 7, of the first fin ring281. As shown in FIG. 2, the first fin ring 281 may be located in thevicinity of the junction of the cylindrical portion 217 and the taperedportion 218 of the core 210. Referring to FIG. 8, which is the heat sink200 of FIG. 2 with an additional fin ring attached thereto, after thefirst fin ring 281 has been pressed onto the core 210 a second fin ring282 may be pressed onto the core 210. The process of pressing fin rings240 onto the core 210 may continue until the surface 212 of the core 210is substantially covered with fin rings 240 as illustrated in FIG. 6.

[0042]FIG. 6 illustrates nine fin rings 240 affixed to the core 210. Thefin rings 240 are referred to individually as the first through theninth fin rings and referenced numerically as 281 through 289respectively. The plurality of fin rings 240 substantially increases thesurface area available on the heat sink 200 for convecting heat to thesurrounding atmosphere. In addition, the fin rings 240 are relativelythin, which increases their ability to convect heat to the surroundingatmosphere by minimizing the air resistance through the fin rings 240 asis described below. As illustrated in FIG. 6, the cooling fins 246 aresubstantially planar and are located on planes that are substantiallyparallel to each other. As described in greater detail below, the planararrangement of the cooling fins 246 forms channels that serve to guideair past the cooling fins 246, which increases convection of heat to thesurrounding atmosphere. The planar arrangement of the fin rings 240 isdescribed below with reference to the schematic illustration of FIG. 5.

[0043] In the embodiment of the heat sink 200 described herein, the finrings 240 are arranged so that the cooling fins 246 are nested, meaningthat they bisect airflow patterns. This nesting is illustrated in FIG. 5between the seventh fin ring 287, the eighth fin ring 288, and the ninthfin ring 289. The cooling fins 246 of the seventh fin ring 287 and theninth fin ring 289 are located on the same plane and thus form an airchannel therebetween. This air channel is bisected by the cooling fins246 of the eighth fin ring 288. This bisection causes some turbulence inthe airflow within the cooling fins 246, which serves to break up orreduce the air barrier layer. Thus, the cooling capability of the heatsink 200 is improved. It should be noted that the nesting of the finrings 240 enables a great number of cooling fins 246 to be associatedwith the heat sink 200.

[0044] Having described the heat sink 200, the fan 110 and other airblowing devices will now be described followed by a description of theassociation between the heat sink 200 and the fan 110.

[0045] Referring again to FIG. 6, the fan 110 may be a conventionalelectric fan. In other embodiments described below, the fan 110 isreplaced with an air blowing device, such as duct work. The fan 110 may,as an example, be of the type commercially available from the MatsushitaElectric Corporation as Model FBA06T12H and sold under the tradenamePANAFLO. The fan 110 may have a rotating portion 112, wherein therotating portion 112 may have a top portion 114, a lower portion, notshown in FIG. 6, and a peripheral side wall 116. A reference axis AA mayextend through the center of the top portion 114 and may besubstantially normal to the top portion 114. As described in greaterdetail below, the reference axis AA may define a center of rotation ofthe rotating portion 112. A direction 130 is used herein to describe therotational direction of the rotating portion 112 about the referenceaxis AA.

[0046] The peripheral side wall 116 of the fan 110 may have a pluralityof circulating fins 118 attached thereto. The circulating fins 118 maybe substantially identical to each other. A first circulating fin 119and a second circulating fin 120 are used as a reference to describe allthe circulating fins 118. The circulating fins 119, 120 may have aninner side 121, an outer side 122, an upper side 124, and a lower side126. The sides may define the boundaries of a surface 128. The innerside 121 may be attached to the peripheral side wall 116 of the rotatingportion 112 in a conventional manner. For example, the circulating fins119, 120 may be adhered to or integrally formed with the side wall 116.The attachment of the circulating fins 119, 120 to the side wall 116 maydefine an angle θ between the surface 128 and the reference axis AA. Theangle θ may, as an example, be about 45 degrees. In one embodiment, theangle θ is equal to 90 degrees minus the angle φ of FIG. 7. As describedin greater detail below, the angle θ may serve to determine thedirection of air flow generated by the fan 110 as the rotating portion112 rotates in the direction 130.

[0047] Having described the fan 110 and the heat sink 200 separately,their association with each other will now be described.

[0048] As illustrated in FIG. 6, the fan 110 may be located adjacent thetop portion 214, FIG. 2, of the core 210. The fan 110 may, as examples,be attached to the core 210 by the use of fasteners, e.g., screws, or itmay be adhered to the core 210. It should be noted, however, that thefan 110 does not need to be physically attached to the core 210 and thatthe fan 110 only needs to be able to force air past the cooling fins246.

[0049]FIG. 5, illustrates the air flow between the fan 110 and the heatsink 200 in one embodiment of the cooling device 100. It should be notedthat for illustration purposes the heat sink 200 illustrated in FIG. 5only shows a limited number of fin rings 240 and cooling fins 246. Asdescribed above, the first circulating fin 119 is positioned at an angleθ relative to the reference axis AA. In one embodiment, the angle θ isapproximately forty-five degrees. The cooling fins 246 are positioned atan angle φ relative to the reference axis AA, which, in the embodimentdescribed herein, is approximately 45 degrees. A reference axis CC mayextend parallel to the end portions 258 of the cooling fins 246 and maybe substantially perpendicular to the surface 128 of the firstcirculating fin 119. An air flow direction 290 commences at the surface128 of the first circulating fin 119 and extends parallel to thereference axis CC, which, in this embodiment, is normal to the surface128. The air flow direction 290 is the direction that air flows as thefirst circulating fin 119 rotates in the direction 130.

[0050] When the rotating portion 112 rotates in the direction 130, thefirst circulating fin 119 forces air to circulate past the cooling fins246. The airflow generated by the rotating first circulating fin 119flows in the air flow direction 290, which is parallel to the referenceaxis CC. The air flow direction 290 is, accordingly, parallel to the endportions 258 and the surfaces 260 of the cooling fins 246. This relationbetween the air flow direction 290 and the cooling fins 246 allows airgenerated by the rotating first circulating fin 119 to pass over thesurfaces 260 of the cooling fins 246 with little resistance. Inaddition, this air flow direction 290 relative to the cooling fins 246reduces any eddy currents that may, in turn, reduce the air flow throughthe heat sink 200. In addition, as described above, the cooling fins 246are thin enough to minimize air resistance, but thick enough to transferheat from the core 210. Thus, the cooling fins 246 cause littleresistance to the air flow through the heat sink 200, which in turn,allows for the maximum convection of heat from the cooling fins 246 tothe surrounding atmosphere. As described above, the cooling fins 246 maybe small enough to minimize the air barrier layer present on theirsurfaces, which in turn increases the cooling capability of the coolingdevice 100.

[0051] The thin cooling fins 246 and their placement relative to eachother allow them to be condensed or “nested” which in turn allows agreater number of cooling fins 246 to convect heat to the surroundingatmosphere. In addition, the placement of the fin rings 240 and thecooling fins 246 create channels for air to flows past the cooling fins246. One such channel is defined by the reference axis CC, which isparallel to the air flow direction 290. Other channels are parallel tothe channel defined by the reference axis CC and other channels bisectthe channel defined by the reference axis CC.

[0052] Referring again to FIG. 6, having described the cooling device100, it will now be described cooling a heat generating device 330 thatis mounted to a top surface 342 of a printed circuit board 340. The heatgenerating device 330 is described herein as being an integrated circuitthat generates heat when it is in use. The heat generating device 330may have a top surface 332 wherein most of the heat generated by theheat generating device 330 flows from the top surface 332 in a direction334. The cooling device 100 may be operatively associated with the heatgenerating device 330 so that the lower portion 216 of the core 210 isin thermal contact with the top surface 332 of the heat generatingdevice 330. In order to assure thermal conductivity between the heatgenerating device 330 and the cooling device 100, the cooling device 100may be attached to the printed circuit board 340 in a conventionalmanner so as to bias the cooling device 100 onto the heat generatingdevice 330.

[0053] When the heat generating device 330 is in use, it generates moreheat than it can dissipate alone. Heat accumulates in the top surface332 of the heat generating device 330 and generally flows in thedirection 334. The heat generated by the heat generating device 330 isabsorbed into the core 210 by virtue of the thermal contact between thetop surface 332 of the heat generating device 330 and the lower portion216 of the core 210. Thus, the temperature of the heat generating device330 is reduced by the absorption of heat into the core 210. The heatabsorbed by the core 210 dissipates to the surface 212 where some of theheat is convected directly to the surrounding atmosphere. Theinterference fits between the fin rings 240 and the core 210 cause themajority of the heat dissipated to the surface 212 of the core 210 totransfer to the fin rings 240 and into the cooling fins 246.

[0054] Simultaneous to heat being absorbed into the core 210 anddissipated to the cooling fins 246, the fan 110 forces air to flow inthe air flow direction 290 past the surfaces 260 of the cooling fins246. More specifically, the fan 110 may draw air into the cooling device100 along an air flow direction 360. The air passes through the heatsink 200 in the air flow direction 290 and is exhausted along an airflow direction 362. Accordingly, the heat in the cooling fins 246 isconvected into the surrounding atmosphere. As described above, thetapered portion 218 of the core 210 enables the air to flow freely fromthe heat sink 200, which in turn increases the amount of air that can beforced through the heat sink 200.

[0055] The rate of heat transfer between the core 210 and the coolingfins 246 is proportional to the temperature difference between thecooling fins 246 and the surface 212 of the core 210. Likewise, the heattransfer from the heat generating device 330 to the core 210 isproportional to the temperature of the core 210. Accordingly, a higherrate of heat transfer from the heat generating device 330 can beaccomplished by significantly cooling the cooling fins 246. Thetemperature of the cooling fins 246 is proportional to their positionrelative to the heat generating device 330, wherein the cooling fins 246positioned close to the heat generating device 330 are hotter than thosepositioned further from the heat generating device 330. By forcingrelatively cool air in the air flow direction 290, all the cooling fins246 are exposed to relatively cool air, which reduces their temperature.The relatively cool cooling fins 246 are, thus, able to transfer heatfrom the surface 212 of the core 210 at a high rate, which in turn,cools the core 210 at a high rate. The cooler core 210 is then able toremove a great amount of heat at a high rate from the heat generatingdevice 330.

[0056] Due to inherent air restrictions in the heat sink 200 caused bythe cooling fins 246, not all the air forced into the heat sink 200 bythe fan 110 passes by the cooling fins 246. For example, the fan 110 maycause air pressure to build up in the cooling fins 246, which in turn,causes some air to leave the heat sink 200 without passing by all thefin rings 240. The heat sink 200 of FIG. 6 shows that some air mayfollow an air flow direction 370 and may be exhausted from the heat sink200 without passing by all of the cooling fins 246. Accordingly, the airfollowing the air flow direction 370 may not be used efficiently.

[0057] Referring to FIG. 9, in order to assure all the air drawn intothe cooling device 100 passes the cooling fins 246, a shroud 350 may beadded to the cooling device 100. The shroud 350 may, as an example, be aduct that fits over the heat sink 200 and does not allow air to escapefrom the heat sink 200 until it has passed by all the cooling fins 246.Thus, all the air entering the cooling device 100 along the air flowdirection 360 is exhausted from the cooling device 100 along the airflow direction 362.

[0058] The shroud 350 may have an upper portion 352 and a lower portion354. The upper portion 352 may substantially encompass the fan, notshown in FIG. 9, and the lower portion 354 may substantially encompassthe heat sink 200. A plurality of openings 356 may be formed into theupper portion 352 in order to facilitate air flow through the coolingdevice 100. More specifically, air may flow in an air flow direction 364through the openings 356 where it joins the air flowing along the airflow direction 360. Accordingly, the openings 356 may serve to increasethe volume of air that passes the cooling fins 246, which in turnincreases the convection of heat to the surrounding atmosphere. Theshroud 350 is illustrated as having slot-shaped openings 364 that areslanted to correlate with the angle of the first circulating fin 119,FIG. 6. The openings 364 described herein are positioned at the angle θrelative to the reference axis AA, which in the embodiment describedherein is forty-five degrees.

[0059] Having described an embodiment of the cooling device 100, otherembodiments of the cooling device 100 will now be described.

[0060] Referring again to FIG. 5, the cooling device 100 has beendescribed here as having the fin rings 240 pressed onto the core 210.Pressing the fin rings 240 onto the core 210 creates interference fitsbetween the fin rings 240 and the core 210, which provide for highthermal conductivity between the core 210 and the fin rings 240. Theinterference fits, however, require that the core 210 and the fin rings240 be manufactured to precise specifications. If precise manufacturingspecifications are not achieved, the fin rings 240 may be loose on thecore 210 or the fin rings 240 may not be able to be pressed onto thecore 210.

[0061] Referring to FIG. 10, the above-described problems of controllingthe specifications of the fin rings 240, FIG. 6, may be overcome by theaddition of compression rings partially encompassing the core 210. Inthis embodiment of the heat sink 200, interference fits between the finrings 240 and the core 210 are not required. A compression ring 380 mayabut the top side of the first fin ring 281. A second compression ring,not shown, may abut the bottom side of the first fin ring 281. Thecompression ring 380 may be a ring of thermally conductive material,such as copper or aluminum, that is pressed onto the core 210 and firmlyabuts the first fin ring 281. Heat in the core 210 may then betransferred to the first fin ring 281 via the compression ring 380.Accordingly, the use of the compression ring 380 permits the first finring 281 to be manufactured to looser specifications than thosedescribed above. In one embodiment, the compression rings forminterference fits with the fin rings and the core when they are pressedtogether. For example, the compression rings may distort to form theinterference fits.

[0062] A plurality of compression rings may be pressed or otherwiseplaced onto the core 210 during the manufacturing process of the heatsink 200. For example, one compression ring, not shown in FIG. 10, maybe pressed onto the core 210 in the vicinity of the lower portion 216.The first fin ring 281 may then be placed over the core 210 so as toabut the compression ring located in the vicinity of the lower portion216. The compression ring 380 may then be pressed onto the core 210 soas to abut the first fin ring 281. Accordingly, the first fin ring 281is sandwiched between compression rings. The compression rings may thenbe forced together to so that the first fin ring 281 is tightlycompressed between them. This compression serves to enhance the thermalconductivity between the compression rings and the first fin ring 281,which in turn enhances the cooling capability of the heat sink 200.

[0063] Referring to FIG. 11, a plurality of compression rings may bepressed onto the core 210. The heat sink 200 illustrated in FIG. 11 issimilar to the heat sink 200 illustrated in FIG. 6, however, the heatsink 200 of FIG. 11 has a plurality of compression rings placed orotherwise pressed onto the core 210. The heat sink 200 may have a topcompression ring 390 located in the vicinity of the top portion 214 ofthe core 210. The heat sink 200 may also have a bottom compression ring392 located in the vicinity of the junction of the cylindrical portion217 and the tapered portion 218 of the core 210. A plurality of innercompression rings 394 may be pressed onto the core 210, wherein one ofthe plurality of inner compression rings 394 is located between each ofthe fin rings 240.

[0064] The heat sink 200 of FIG. 11 may be manufactured by firstpressing the bottom compression ring 392 onto the core 210. The firstfin ring 281 may then be slipped over the core 210 and placed near thebottom compression ring 392. An inner compression ring 394 may then bepressed onto the core so as to sandwich the first fin ring 281 betweencompression rings. The second fin ring 282 may then be slipped over thecore 210 to abut the previously pressed on inner compression ring 394.The process of alternating fin rings 240 and inner compression rings 394continues until all of the fin rings 240 have been placed onto the core210. Accordingly, an inner compression ring 394 is located between eachfin ring 240. The top compression ring 390 may then be pressed onto thecore 210. In order to assure that thermal contact exists between the finrings 240 and the compression rings 390, 392, 394, the top compressionring 390 and the bottom compression ring 392 may be pressed together.This will cause the fin rings 240 to contact all the compression rings390, 392, 394, which increases the thermal conductivity between thesurface 212 of the core 210 and the fin rings 240.

[0065] Referring again to FIG. 6, in one embodiment of the coolingdevice 100, the core 210 may be a heat pipe or have a heat pipe locatedtherein. A heat pipe is a device that is known in the art and serves torapidly transfer heat. Thus, the interior of the core 210 may be apartially evacuated chamber containing a small amount of a liquid. Whenthe core 210 is cool, the liquid is located in the vicinity of the lowerportion 216 of the core 210. The liquid evaporates when it is heated bythe heat generating device 330. The vapor from the evaporated liquidcondenses on the sides of the core 210 and, thus, transfers its heat tothe sides of the core 210. The heat may then quickly transfer to thesurface 212 of the core 210. The heat may then be convected to thesurrounding atmosphere as described above. The use of the heat pipesubstantially increases the heat transfer through the core 210, which inturn increases the cooling capability of the cooling device 100.Examples of heat pipes are disclosed in the following U.S. patents andpatent applications, which are all hereby incorporated by reference forall that is disclosed therein: U.S. Ser. No. 09/376,627 of Wagner et al.for COOLING APPARATUS FOR ELECTRONIC DEVICES; U.S. Pat. No. 5,694,295 ofMasataka et al. for HEAT PIPE AND PROCESS FOR MANUFACTURING THE SAME.

[0066] The heat sink 200 has been described herein as having a pluralityof cooling fins 246 that extend radially from the core 210. Otherembodiments of the heat sink 200 have different cooling finconfigurations as described in greater detail below.

[0067] One embodiment of a fin configuration is illustrated in FIG. 12and uses a ribbon-type cooling fin, which is sometimes referred toherein as a cooling ribbon 400. The cooling ribbon 400 may, as anexample, be constructed from a single piece of a thermally conductivematerial, such as a sheet of copper or aluminum. Alternatively, thecooling ribbon 400 may be extruded in a conventional manner. The coolingribbon 400 may have a plurality of contact portions 410 and end portions412. The contact portions 410 may serve to contact the surface 212 ofthe core 210 and may, thus, be points where heat is transferred from thecore 210 into the cooling ribbon 400. The end portions 412 may beportions of the cooling ribbon 400 that are located furthest from thesurface 212 of the core 210. A plurality of inner air channels 420 maybe located between the surface 212 of the core 210 and the end portions412. A plurality of outer air channels 422 may be located between thecontact portions 410 and the cooling ribbon 400.

[0068] The cooling ribbon 400 may be pressed onto the core 210. Forexample, in one embodiment of the heat sink 200, a single cooling ribbon400 is pressed onto the core 210 and extends at least a portion of thelength of the cylindrical portion 217, FIG. 3 of the core 210. Inanother embodiment of the heat sink 200, a plurality of cooling ribbons400 are pressed onto the heat sink 200 and extend at least a portion ofthe length of the cylindrical portion 217 of the core 210. Heat in thesurface 212 of the core 210 transfers to the cooling ribbon 400 via thecontact portions 410. The heat is then convected into the surroundingatmosphere. An air blowing device, such as a fan or duct work, not shownin FIG. 12, may force air in the inner air channel 420 and the outer airchannel 422 to increase the convection of the heat in the inner airchannel 420 to the surrounding atmosphere.

[0069] Referring to FIG. 13, as with other embodiments of the heat sink200, a shroud 430 may be placed over the heat sink 200. The shroud 430,in conjunction with an air blowing device, forces air in the outer airchannel 422 to remain in the outer air channel 422 throughout the lengthof the shroud 430. Accordingly, air in the outer air channel 422 is usedmore efficiently, which improves the overall efficiency of the coolingdevice 100.

[0070] Referring to FIG. 14, in another embodiment of the heat sink 200,the cooling fins 246 extend axially along the length of the core 210similar to the ribbon-type cooling fin 400 of FIG. 12. Morespecifically, the cooling fins 246 may extend substantially parallel tothe reference axis AA. This cooling fin configuration may be used whenthe air flow from the air blowing device 110 extends substantiallyparallel to the reference axis AA. For example, in the embodiment wherethe air blowing device 110 is duct work, the airflow generated by theair blowing device 110 will likely extend along the reference axis AA asshown in FIG. 14. Thus, the benefits of having the cooling fins 246parallel to the air flow as described above are maintained.

[0071] The cooling fins 246 shown in FIG. 14 and the cylindrical portion217 of the core 210 may be extruded as a single piece. Accordingly, heattransfer between the core 210 and the cooling fins 246 is may beimproved. As with the other embodiments of the cooling device 100, ashroud, not shown in FIG. 14, may substantially encompass the core 210and the cooling fins 246.

[0072] The cores 210 of the heat sinks 200 described above mayalternatively be constructed from two pieces of material as shown inFIG. 15. The cylindrical portion 217 may be manufactured separate fromthe tapered portion 218. The two portions may then be assembled so as toprovide thermal contact therebetween. In the embodiment shown in FIG. 15a screw 440 is used to attach the tapered portion 218 to the cylindricalportion 217. It should be noted that other attaching mechanisms, such asthe use of an adhesive may be used to attach the two portions together.In another embodiment, a heat conductive compound may be located betweenthe cylindrical portion and the tapered portion 218 in order to improvethe thermal conductivity between the two portions.

[0073] The embodiment of the core 210 shown in FIG. 15 facilitatesmanufacturing the core 210 and any cooling fins that may be attachedthereto by extrusion. With additional reference to FIGS. 12 and 14, anyof the embodiments of the heat sink 200 having cooling fins that extendalong the reference axis M may be extruded from the same piece ofmaterial as the core 210. The extruded core and cooling fin combinationmay be cut to an appropriate size. The tapered portion 218 may then beadded to the combination to form the heat sink 200.

[0074] Referring again to FIG. 6, the fin rings 240 have been describedas being adjacent to the surface 212 of the core 210. It is to beunderstood that the fin rings 240 may be attached to the core bynumerous methods. For example, the fin rings 240 may be pressed onto thecore 210. In another example, the core fin rings 240 may be soldered orbrazed to the core 210.

[0075] Another embodiment of a shroud 450 is shown in FIG. 16. As shownin FIG. 16, the shroud 450 does not extend the full length of the fan110. This embodiment of the shroud 450 may increase air flow by causingair to enter the cooling device 100 by way of an airflow 460 and anairflow 462.

[0076] While an illustrative and presently preferred embodiment of theinvention has been described in detail herein, it is to be understoodthat the inventive concepts may be otherwise variously embodied andemployed and that the appended claims are intended to be construed toinclude such variations except insofar as limited by the prior art.

What is claimed is:
 1. A heat sink for removing heat from a heat source,said heat sink comprising: a core member comprising at least one firstsurface adapted to contact at least a portion of said heat source; atleast one outer peripheral surface located on said core member; and atleast one cooling fin device comprising at least one inner peripheralsurface and at least one cooling fin associated therewith, said at leastone inner peripheral surface of said cooling fin device being adjacentsaid at least one outer peripheral surface of said core member; at leasta portion of said at least one outer peripheral surface being tapered,wherein the circumference of said at least one outer peripheral surfacein the proximity of said first surface being greater than thecircumference of said at least one outer peripheral surface not in theproximity of said first surface.
 2. The heat sink of claim 1, whereinthe circumference of said at least one outer peripheral surface isgreatest at a junction of said at least one outer peripheral surface andsaid at least one first surface.
 3. The heat sink of claim 1, whereinsaid at least a portion of said at least one outer peripheral surfacebeing tapered forms a continuous surface.
 4. The heat sink of claim 1,wherein said at least one cooling fin provides at least one air channel,said at least one air channel being parallel said at least one outerperipheral surface of said core member, and said at least one airchannel being adjacent said at least one cooling fin.
 5. The heat sinkof claim 4, and further comprising at least one second cooling fin,wherein said at least one second cooling fin bisects said at least oneair channel.
 6. The heat sink of claim 4, wherein said at least one airchannel spirals said core member.
 7. The heat sink of claim 1, whereinsaid at least one cooling fin device comprises at least one collarmember having a plurality of cooling fins attached thereto and whereinsaid at least one collar member has at least one inner peripheralsurface.
 8. The heat sink of claim 1, wherein an interference fit existsbetween said at least one outer peripheral surface of said core memberand said at least one inner peripheral surface of said at least onecooling fin device.
 9. The heat sink of claim 1, and further comprisinga shroud having at least one inner surface, wherein said at least oneinner surface is located adjacent said at least one cooling fin.
 10. Theheat sink of claim 9, wherein said shroud has a first portion and asecond portion, wherein said first portion is located adjacent said atleast one cooling fin, and wherein said second portion extends beyondsaid core member.
 11. The heat sink of claim 10, wherein said secondportion has at least one slot formed therein.
 12. The heat sink of claim11, and further comprising a fan located opposite said at least onefirst surface; said fan having at least one circulating fin associatedtherewith; said at least one circulating fin being at an angle relativeto a centerline of said core; said at least one slot formed in saidsecond portion of said shroud being at the same angle as said at leastone circulating fin.
 13. The heat sink of claim 1, wherein said coremember comprises a heat pipe.
 14. The heat sink of claim 1, wherein saidcore member further comprises a core member first portion oppositelydisposed said at least one first surface, and wherein said heat sinkfurther comprises an air blowing device located in the vicinity of saidcore member first portion.
 15. The heat sink of claim 14, wherein saidair blowing device is a fan.
 16. The heat sink of claim 14, wherein saidair blowing device has an air path associated therewith, wherein said atleast one cooling fin has a substantially planar surface, and whereinsaid air path is substantially parallel to said at least one cooling finsurface.
 17. The heat sink of claim 14, wherein said air blowing devicecomprises at least one blower fin, wherein said at least one blower finhas a blower fin surface , wherein said at least one cooling fin has asubstantially planar surface, wherein an air path is substantiallyparallel to said at least one cooling fin surface, and wherein said airpath is substantially perpendicular to said blower fin surface.
 18. Theheat sink of claim 1, wherein said core member further comprises a coremember first portion oppositely disposed said at least one firstsurface, wherein said core member extends along an axis between saidfirst surface and said first portion, wherein said cooling fin comprisesat least one cooling fin surface, and wherein said at least one coolingfin surface is substantially parallel to said axis.
 19. The heat sink ofclaim 1, wherein said at least one cooling fin has a first end and asecond end, wherein both said first end and said second end are portionsof said at least one inner peripheral surface of said at least onecooling fin device.
 20. The heat sink of claim 1, wherein each of saidplurality of cooling fin devices comprise a first side and a second sideand wherein said heat sink further comprises: at least one collar,wherein each of said at least one collar has at least one innerperipheral surface having a perimeter associated therewith, and whereinsaid outer peripheral surface of said core member has a perimeterassociated therewith that closely corresponds to said perimeter of saidplurality of collars; wherein said inner peripheral surfaces of saidplurality of collars form interference fits with said outer peripheralsurface of said core member; and wherein said first side and said secondside of at least one of said plurality of cooling fin devices abut acollar.
 21. The heat sink of claim 1, wherein said at least a portion ofsaid core member and said at least one cooling fin device are extrudedfrom a single piece of material.
 22. A method of manufacturing a heatsink, said method comprising: providing a core member having at leastone outer peripheral surface and a first surface, said first surfacebeing adapted to be located adjacent a heat source, at least a portionof said at least one outer peripheral surface being tapered, wherein thecircumference of said at least one outer peripheral surface in theproximity of said first surface is greater than the circumference ofsaid at least one outer peripheral surface not in the proximity of saidfirst surface; and pressing at least one cooling fin device onto saidcore member, said at least one cooling fin device comprising at leastone cooling device inner peripheral surface and at least one coolingdevice cooling fin associated therewith.
 23. The method of claim 22,wherein said pressing forms an interference fit with said at least oneouter peripheral surface of said core member.
 24. The method of claim22, wherein said core member further comprises a core member firstportion oppositely disposed said at least one first surface, and furthercomprising providing an air blowing device located in the vicinity ofsaid core member first portion.
 25. The method of claim 24, wherein saidair blowing device has an air path associated therewith, wherein said atleast one cooling fin has a substantially planar surface, and whereinsaid air path is substantially parallel to said at least one cooling finsurface.
 26. The method of claim 24, wherein said air blowing devicecomprises at least one blower fin, wherein said at least one blower finhas a blower fin surface, wherein said at least one cooling fin has asubstantially planar surface, wherein an air path is substantiallyparallel to said at least one cooling fin surface, and wherein said airpath is substantially perpendicular to said blower fin surface.
 27. Themethod of claim 23, wherein said core member further comprises a coremember first portion oppositely disposed said at least one firstsurface, wherein said core member extends along an axis between saidfirst surface and said first portion, and wherein said at least onecooling fin surface is substantially parallel to said axis.
 28. Themethod of claim 23, and further comprising said at least one cooling findevice with a shroud.
 29. The method of claim 23, and further comprisingpressing at least one collar onto said core member; wherein said atleast one collar forms an interference fit with said outer peripheralsurface of said core member; and wherein said at least one collar abutssaid at least one cooling fin device.
 30. A method of cooling an object,said method comprising: locating a heat sink adjacent at least a portionof said object, said heat sink comprising: a core member comprising atleast one first surface adapted to be located adjacent said at least aportion of said object; at least one outer peripheral surface located onsaid core member; and at least one cooling fin device comprising atleast one inner peripheral surface and at least one cooling finassociated therewith, said at least one inner peripheral surface of saidcooling fin device being adjacent said at least one outer peripheralsurface of said core member; at least a portion of said at least oneouter peripheral surface being tapered, wherein the circumference ofsaid at least one outer peripheral surface in the proximity of saidfirst surface being greater than the circumference of said at least oneouter peripheral surface not in the proximity of said first surface;forcing air past said at least one cooling fin device.
 31. The method ofclaim 30, wherein said core member comprises a second surface locatedopposite said at least one first surface, said forcing air comprisesforcing air past said at least one cooling fin in a direction from saidsecond surface toward said at least one first surface.
 32. The method ofclaim 30, wherein said forcing air comprises locating an air blowingdevice proximate said at least one first surface and using said airblowing device to force air past said at least one cooling fin device.33. The method of claim 32, wherein said air blowing device is a fan.34. The method of claim 30, wherein said heat sink further comprises ashroud having at least one inner surface, wherein said at least oneinner surface is located adjacent said at least one cooling fin device.